VestCards is a flashcard study platform I founded and built for Brazilian university entrance exams (vestibular) — covering ENEM, FUVEST, Unicamp, and more. The idea came out of a real experience: during the pandemic, friends who got into top universities like USP, Unicamp, UNESP, and FAMERP had accumulated a massive bank of study flashcards, and I saw an opportunity to turn that into something useful for every student going through the same journey. I’ve been running and developing it since 2020, and it’s still growing.
What It Does
VestCards combines a curated library of over 250 subject decks with a spaced repetition algorithm calibrated to help students retain 95% of studied content. Instead of passive review, students actively engage with cards and the algorithm schedules revisits based on individual performance — prioritizing what each student most needs to see. A statistics dashboard tracks progress, highlights weak spots, and keeps study sessions purposeful.
The platform also supports user-created decks, making it flexible for students who want to supplement the existing library with their own material.
Stack & Implementation
I built VestCards using TypeScript and Next.js for the frontend, tRPC for end-to-end typesafe APIs, PostgreSQL as the main database, and Redis for caching and performance-critical operations. I also shipped it as a React Native app with a fully responsive UI, which increased active users by 25%.
Payments & Monetization
I integrated Asaas, a Brazilian payment API, to support the platform’s subscription model. This covers the full checkout experience — subscription plans, promotional coupons, and multiple payment methods including credit card, PIX, and boleto. The payment flow is covered with both E2E and integration tests to ensure reliability across the full transaction lifecycle.
Impact
- Grew to 4,500+ registered students across Brazil
- React Native implementation increased active users by 25%
- Helping students from all over Brazil get into universities like USP, Unicamp, UNESP, and FAMERP